1. Field of the Invention
The present invention relates to improvement of a ball suction head, in a ball mount apparatus, for mounting solder balls, solder bumps, or the like, on a substrate or a wafer. The present invention was chiefly developed with the primary object of a suction head for sucking solder balls in a BGA (Ball Grid Array) solder ball mount apparatus for mounting solder balls all over a wafer.
The present application is based on Japanese Patent Application No. Hei. 11-156998, which is incorporated herein by reference.
2. Description of the Related Art
In a BGA solder ball mount apparatus, a ball suction head 1 for sucking solder balls 7 has, in its lower surface, a large number of suction holes 2 for sucking the solder balls 7, as shown in FIG. 6. The ball suction head 1 is decompressed by vacuum means so as to suck the solder balls 7 from a solder ball supply tray 8. In the background art, the number of solder balls 7 sucked by the ball suction head 1 at a time was about 200, and there was therefore no special problem. However, with recent miniaturization of the solder balls 7 and with recent technological developments in mounting solder balls 7 on a wafer, a large number (tens of thousands) of solder balls 7 are sucked by the ball suction head 1.
When the ball suction head 1 sucks a large number of solder balls 7 at a time or when the diameter of each ball suction hole 2 of the ball suction head 1 increases, it is required to increase the size of the decompression means for decompressing the ball suction head 1. Thus, there arises a problem in terms of space or usefulness. In addition, when the ball suction head 1 sucks a large number of solder balls 7 at a time, there arises a problem that such a large number of solder balls 7 cannot be sucked uniformly if the capacity of the decompression means goes down.
In order to solve the foregoing problems, it is a first object of the present invention to provide a ball suction head which can suck balls uniformly with decompression means which is small in size and low in capacity. It is a second object to provide a ball suction head in which the suction area to suck the solder balls is divided and the solder balls are sucked so that the solder balls are sucked in the suction holes in an area larger than the capacity of the decompression means. It is a third object to eliminate errors in sucking solder balls so as to shorten the suction time.
In order to attain the foregoing objects, according to the present invention, a mask is provided in a ball suction head for a ball mount apparatus which has a large number of ball suction holes and is connected with a decompression source through a suction path. The mask provides with one position at which suction force acts on predetermined ones of ball suction holes and another position at which suction force does not act on the predetermined ones of ball suction holes.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.